Might sound a bit silly but......get a backpack or camelback etc, load it up with weights/rocks etc until you're close to that weight and then sit on the bike and adjust the PSI until you have the right SAG.

Originally Posted by BIke N Gear

Yea, I know that. I am trying to set this up for someone else. I don't weigh that much. I was just trying to get an idea of around how many psi.